Most folks head to Kununurra etc for their first GA job. Darwin is usually where you go for your twin job etc. However, it's been a good 10 + years since I was there so my info may be out of date.
There's "young" 18 year olds and "mature" 18 year olds.
Most folks go to the places where you're likely to get a start and pick up bar work etc. Anything. Here is where you get a chance to prove you're the latter.
Good luck, it is an adventure.